A spoiler is a type of moving surface structure which is used to break up the airflow around an aerodynamic surface such as an aircraft wing, in order to slow the movement of the aircraft through the air or to decrease the lift on the surface. On the majority of large aircraft, conventional spoilers are stowed flat to the wing outer mould line during cruise and only deploy upwards into the air flow to spoil lift so that the aircraft looses height during landing or descent. Usually, the spoilers deploy through an angle of up to 55 degrees to spoil lift.
Until recently, spoilers have only been used to decrease lift. However, more recent developments in aircraft design now also require spoilers to droop to aid high lift devices on the trailing edge of the wings, such as the flaps.
Although spoilers may only droop by an angle of up to 15 degrees to aid lift, providing for the droop function results in gaps being formed in the top skin surface between the spoiler and the trailing edge of the fixed wing at all the positions where the spoiler is hingedly mounted to the fixed wing during cruise. These gaps result in the generation of excessive noise and reduce efficiency which is unacceptable, especially now that there are increasingly more stringent requirements for noise reduction in populated areas as well as demands for more efficient aircraft. In larger aircraft the additional noise generated as a result of the formation of gaps in the hinge area is particularly noticeable, as such aircraft can have up to seven spoilers per wing with a minimum of two hinges per spoiler. Sealing in the hinge area between the spoilers and the fixed wing has therefore become a more critical aspect in aircraft wing design.
Although conventional elastomeric materials are often employed for the purpose of sealing between a spoiler and the fixed wing, it has been found that this type of seal is not feasible considering the range of movement throughout which sealing is required when a spoiler is required to droop to aid lift in addition to its normal function of raising to spoil lift.
The present invention therefore seeks to provide improved sealing in the hinge area between a moving aero surface structure and a fixed wing to improve efficiency and reduce noise during take-off and landing and with the aim of preventing or reducing bleed through of air from the high pressure below the wing to the low pressure above the wing.
The present invention may also provide an overall weight reduction to an aircraft. In current designs, the moving aero surface structure is provided with hinge lugs that cooperate with a mating clevis on the fixed wing structure. However, the present invention potentially allows for the hinge lugs to be provided on the fixed structure and the mating clevis provided on the moving aero structure. This results in a much better load introduction into the aero surface and therefore facilitates a much more lightweight overall design for the aircraft. When the hinge lugs are provided on the fixed structure without the improved sealing arrangement provided by embodiments of the present invention, the exposed slots in the upper aero surface are much wider and so any benefit obtained as a consequence of the weight reduction would be outweighed by the inefficiency caused by the wider slots.